Projection-screen.



O. BUBCHNBR.

PBUJECTION SCREEN.

APPLIoATIon rum) JULY 11, 1910.

Patented July 11, 1911.

UNITED STATES PATENT OFFICE OSWLD BUECHNER, OF ZURICH, SWITZERLAND, ASSIGNOB, BY DIRECT AND MESNE ASSIGNMENTS, TO PRANA GESELLSCHAFT FR TAGESLICHTQPROJEKTION MIT BESCHRNKTEB HAFTUNG, 0F HAMBURG, GERMANY.

PROJ' ECTION-SCREEN.

Specification of Letters Patent.

Patented July 11, 191 1.

Application led July 14, 1910. Serial No. 571,940.

' 'lo all whom it may concern:

Be it known that I, OswALn BUuonNEn, a citizen of the Republic of Switzerland, residing at (i3 Forchstrasse, Zurich, Switzerland, have invented certain new and useful 'Improvements in Projection-Screens, of

,projection not only in rooms fully lighted by brilliant artificial light or by bright sunlight admitted through the windows, but even in the open air during the daytime.

The invent-ion is based on two characteristic features; on the one hand a pane of transparent material of suitable shape, constituting a projection screen; and on the other hand, the peculiar treatment to which the pane is subjected. The arrangement may consist of a pane (made in a' single piece or built up of separate pieces), the surface of which is given local refractive dispersive properties by means of concave or convex lenticular (that is, lens-like) grainings.

As to the mode of treating the anes, they are covered with a thin, meta ic, or other coating, the purpose of which is to reduce the amount of light reflected from the pane into the eyes of the spectators, so that the pane will have a dark appearance in daylight. F or producing such a coating or recipitate,'p1atinum may be employed. he purpose may also be effected by'a plying a coatin of dark coloring matters mixed with suitab e agglutinants. The criterion to be followed in choosing these substances, is that they shall give the pane a dark appearance in daylight. When a sheet or pane of transparent material is made as hereinbefore de-v scribed, pencils of light transmitted through it from a projectin y apparatus will be d1s. persed by the associated refracting units of curved configuration in such manner as to cause the projected icture to appear on the screen, where it may eobserved by the s ectators, and if the screen is then treate by the thin coating referred to, in such manner as to suppress or reduce the reflection of incident light into thc eyes of the spectators, so that the screen has a dark aplwaranec in daylight, the predominance of the projected picture over the reflected light is emphasized.

Referring to the drawings,-1 `igure 1 is a section through a pane embodying my in! vention; Fig. 2 is a view of the surface of a coarsely rained pane, and Fig. 3 is a view of the sur ace of a finely grained pane.

In the drawing, a represents the scrcen of transparent material, such as glass, for ex ample, made up in a single piece or built up of a number of pieces.

The lens-like pattern constituting the image-display surface (inthis instance, made up of concave configurations) is indicated by b, and c indicates the thin coating.

The optical phenomena produced when this screen is used are: First: the dispersion ofthe rays forming the pencils of ligh which fall upon the lenticular or associate refracting units of curved configuration, b. the refraction incident to such configuration, so as to direct and distribute the several rays forming each of said pencils to all parts of the space to be occupied by the spectators, With the conservation of the projected light incident to such dispersion; second: the sensation of continuity of the image produced upon the retina of the eye of the spectutor by the slightly separated beams of light issuing from points upon the several associated refracting units of the screen; third: the greater extent to` which the curved surfaces disperse the refiected rays by diverging or scattering them than they disperse the refracted rays by bending them in the desired directions; and fourth: the capacity of the coating to reduce the amount of light reflected from the screen into the eyes of the spectators, While still permitting the passage of the greater part of the refracted rays which are directed to the same points. b

What I claim is:

1. A projection screen of transparent material, having its image-display surface made up of associated refracting units of curved configuration.

2- A projection screen of transparent material having its image-display surface made up of justaposed lenticulae.

3. A projection screen of 4transparent material, having its image-display surface made up of uniformly distributed associated refracting units of curved configuration.

4. A projection screen of transparent ma- 5 terial, having the image-display surface made up of identical juxtaposed lentieulae.

5. A projection screen of transparent material, having its image-display surface made up of associated refracting units of cur`ved 10 configuration, said screen'having a coating adapted to .,reduce the 'amount of light refected from the screen into the eyes of the spectators. v* v In testimony whereof, I afxmy signature in the presence of two witnesses.

OSWALD BUECHNE It.

Witnesses:

HANS BUoL, CARL CUUn. 

